Demirina meridionalis Özcan, 1994

SIMMONS, MICHAEL & BIDGOOD, MICHAEL, 2023, “ Larger ” Benthic Foraminifera Of The Cenomanian. A Review Of The Identity And The Stratigraphic And Palaeogeographic Distribution Of Non-Fusiform Planispiral (Or Near-Planispiral) Forms, Acta Palaeontologica Romaniae 19 (2), pp. 39-169 : 64-66

Demirina meridionalis Özcan, 1994

Reference Illustration & Description

Özcan (1994), Pls. 1-2, Fig. 2 , p. 3-4 .

The broadly diamond-shaped apertural face with an acute to subangular periphery, and inner partitions (septula) which project inwards from the chamber wall leaving an empty space in the median part of the chamber is characteristic ( Kaminski, 2000; Mikhalevich, 2004b). The internal partitions are more numerous and complex than in Merlingina and the periphery of the adult chamber is angular/subangular rather than broad and “flat”. See the Species Key Chart (Appendix) for diagnostic and other characteristics.

Deuterospira pseudodaxia may be a synonym, but poor illustrations make confirmation difficult.

Stratigraphic Distribution

?Early-middle? Cenomanian.

D. meridionalis was first described from the undifferentiated Cenomanian Karadut Formation of south-east Turkey ( Özcan, 1994), where it occurs reworked into synchronous (?) deeper-water deposits. It is recorded from the lower part of the formation with Praealveolina grp. cretacea , Orbitolina sp. and Rotalipora sp. , suggesting an age no younger than middle Cenomanian. It was subsequently reported from the platformal Derdere Formation of south-east Turkey by Özkan & Altiner (2019).

Cenomanian Paleogeographic Distribution

Eastern Neotethys.

So far reported only from southeast Turkey.

Figures

Fig. 2 Some morphological descriptions and visualisations of wall and/or chamber components of planispiral or part-planispiral LBF taxa. (a after Hamaoui & Saint-Marc, 1970; b-f after Hottinger, 2006; G: after Vicedo et al., 2013; h after Consorti et al., 2015; j after Consorti et al., 2018). Other abbreviations shown in image j are bl=basal layer; cs=conical spaces; if=intercameral foramina and sc=socculi crest.

Fig. 3 Cenomanian paleogeography with regions indicating the location of most planispiral LBF in this study. There are a few additional records from, for example, Peru, Afghanistan and Tibet. (Base paleogeographic map courtesy of Halliburton).

Fig. 4 Distribution map of type descriptions/specimens in this study.